1. Field of the Invention
The present invention relates to a fuel cell. More particularly, the invention relates to a fuel cell with its cells disposed in a planar arrangement.
2. Description of the Related Art
A fuel cell is a device that generates electricity from hydrogen and oxygen so as to obtain highly efficient power generation. A principal feature of a fuel cell is its capacity for direct power generation which does not undergo a stage of thermal energy or kinetic energy as in conventional power generation. This presents such advantages as high power generation efficiency despite the small scale setup, reduced emission of nitrogen compounds and the like, and environmental friendliness on account of minimal noise or vibration. A fuel cell is capable of efficiently utilizing chemical energy in its fuel and, as such, environmentally friendly. Fuel cells are therefore envisaged as an energy supply system for the twenty-first century and have gained attention as a promising power generation system that can be used in a variety of applications including space applications, automobiles, mobile devices, and large and small scale power generation. Serious technical efforts are being made to develop practical fuel cells.
In particular, polymer electrolyte fuel cells feature lower operating temperature and higher output density than the other types of fuel cells. In recent years, therefore, the polymer electrolyte fuel cells have been emerging as a promising power source for mobile devices such as cell phones, notebook-size personal computers, PDAs, MP3 players, digital cameras, and electronic dictionaries and books. Well known as the polymer electrolyte fuel cells for mobile devices are planar fuel cells, which have a plurality of single cells arranged in a plane. And as a fuel to be used for this type of fuel cells, hydrogen stored in a hydrogen storage alloy or a hydrogen cylinder, as well as methanol, is the subject of continuing investigations.
With a planar fuel cell with its cells arranged in a plane, current collectors are installed in contact with the surfaces of electrodes (anodes and cathodes) to collect electric power from the respective cells. In such an arrangement where the current collectors provided in contact with the surfaces of electrodes, the current collectors must be pressed against the electrodes by screws or other fastening members to ensure stable contact between the electrodes and the current collectors. As a result, the portions occupied by the fastening means present an impediment to attempts at further downsizing the fuel cell.